1. Field of Invention
The present invention relates to microwave containers for popping popcorn. More particularly, the present invention relates to microwave containers for popping popcorn which comprise a microwave transparent container for cooking or popping the corn and an attached essentially microwave opaque container for containing the popped corn and preventing the popped corn from burning.
2. Prior Art
It is known that microwaves are a form of electrical energy that are similar to radio waves. These waves are disseminated within a microwave cavity in a random fashion. They bounce off the walls of the cavity, usually numbering six (counting the walls and the top and the bottom), and the energy is radiated onto, and reflected off the walls of the cavity. Liquids generally react to microwaves more than solids do as the molecules are easier to move, generally due to the amorphous nature of the liquids. Foods consist primarily of some type of liquid or moisture, and on a cellular level, organic foods can consist of as much as 80% water or more. Even popcorn contains its amount of water.
Although the microwave spectrum may be considered to extend from about 0.3 to 300 gigahertz, with the corresponding wave lengths being from one meter to one millimeter, microwave radiation will usually be in the range of 0.3 to 50 gigahertz, and as a practical matter, in the United States, will be within the range of 0.8 to 3 gigahertz (wavelengths of 0.375 to 0.10 meters respectively) because of the uses of the 0.915 and 2.45 gigahertz bands (wavelengths of 0.328 meters to 0.122 meters respectively). It is to be noted that as the frequency increases the wavelength decreases.
Widely stated, microwaves have a typical wavelength of 100 centimeters to 0.1 centimeters (correspondingly the frequencies are 0.3 gigahertz and 300 gigahertz respectively as stated above), and the microwaves are preferably at a frequency of 2450 megahertz, which is the frequency reserved for industrial, scientific, and medical uses of the shorter radio waves. The frequency of 2450 megahertz corresponds to a wavelength of approximately 12 centimeters.
Materials such as plastics and ceramics are known to be transparent to microwave radiation, and materials such as stainless steel and silver are opaque to microwaves as they are conductors and microwaves, by the nature of their high alternating frequency remain on the surface of these materials and do not penetrate, and hence are "opaque" to this form of radiation.
Pillsbury, Orville Redenbacher, and others have marketed packaged popcorn for microwaves in which the popcorn, oil, and seasoning are in a sealed bag and the sealed bag is placed in a microwave oven for popping. The bag, although transparent to microwaves, is opaque to light and hence to viewing and it is difficult to tell when the popping process is finished, resulting in a more than occasional burning of the popcorn, and in other occasions excessive unpopped corn.
Other available microwave transparent containers for popping popcorn, such as Anchor Ovenware's Microware Popcorn Popper, possess no preferential microwave opaque section or container, and rely on the sound of popping (or actually the lack of it) to notify the user that the popping process is finished, or the user must visually note, if the container is transparent to light, that the popping is finished.
Another problem which makes it difficult to tell when the popping is finished, lies in the nature of where to place the item such as popcorn to be popped for consistent results, especially when relying on timing mechanisms. The random nature of the radiation, and the slight difference in placement making consistent timing difficult, what takes 4 minutes one time, takes 5 minutes the next, an increase or difference of 25% in cooking time, hence attempts at using timers results in more than occasional under popping of the corn or burning of the corn.
Robert L. Klamm and Maurice R. Day (U.S. Pat. No. 4,055,252 issued on Oct. 25, 1977) disclose a "Container Liquid Level Detector Apparatus". The disclosure states that a conductive material, such as liquid in a glass container C, will decrease the microwave signal level which passes through the glass container C in proportion to the quantity of such liquid (conductive material) present, and that the received signal is amplified through a variable high gain A.C. amplifier in order to accommodate variations in gain of transmitting and receiving units. This allows the rejection system embodied in the inspection means to reject the container C which has an excessive residual or unacceptable quantity of liquid and remove it from the assembly line. The frequency used for the microwave transmitter is 10.525 gigahertz. The received signal strength is affected by the dielectric constant of the material or media between the sensors, the dielectric constant of water being approximately 80 compared to that of 2.5 for glass.
Marvin L. Bright, Jr. ( U.S. Pat. No. 4,188,769 issued on Feb. 19, 1980) disclosed a process for sealing a container formed from a polymer such as homopolymers, copolymers, and terpolymers, the apparatus of which comprises a source of microwave energy 1 such as a magnetron, and a rectangular waveguide 3 which has an opening 5 therein for the insertion of the container end portion to be sealed. With this disclosed method, the waveguide 3 retains the radiation within the guide 3 and the articles 11 remain outside the microwave field, contained by the container 9 and protected by the waveguide 3.
John J. Austin (U.S. Pat. No. 4,248,901 issued on Feb. 3, 1981) disclosed a "Combination Package and Sleeve Support Means" that comprises of two containers housing an expandable food product which are placed in face-to-face juxtaposition; and a sleeve complemental in shape to the exterior panels of the facing containers which is wrapped around the containers to form a unitized package. The sleeve is bisected by a perforated score line which enables the sleeve to be separated into two pieces. This embodiment is described in the disclosure as being suitable for containing corn kernels and cooking oil for forming popcorn. The embodiment includes an expandable polyethylene liner and is disposable after use. With this type of embodiment, it is impossible to observe the corn popping as the container housing is made of paperboard or a paperboard lamination and thus opaque to popcorn viewing, and as such difficult to discern when the popping process is finished and thus avoid burning the popped corn, and in no way does the disclosed embodiment cooperate with the microwave environment, other than that of it being transparent to microwaves. The disclosure also notes that the embodiments have no metallic elements or components which absorb microwave energy and heat.
Another patent of John J. Austin (U.S. Pat. No. 4,304,327 issued on Dec. 8, 1981) which was copending to his U.S. Pat. No. 4,248,901 discloses a "Container Unitizer Sleeve and Support" which are used to retain the afore mentioned containers in the face-to-face relationship. Again the disclosure notes that the embodiments have no metallic elements or components which absorb microwave energy and heat.
Melvin L. Levinson (U.S. Pat. No. 3,985,991 issued on Oct. 12, 1976) disclosed a method of using a microwave-reflective, heat conductive food container contained within a microwave permeable, non-lossy, heat-insulating, porous body wherein said body is so disposed as to absorb and disperse lossy liquid which evaporates from a cooking foodstuff and condenses on the reverse side of the food container when a frozen foodstuff, in direct thermal contact with the obverse side of the food container, cools the reverse side below its dew point. With this method at least one side of the opaque heat-conductive food container must be transparent to microwaves and the container base 3 is constructed of a microwave-permeable, porous material which absorbs condensed liquid, as the capillary action of a blotter, from surface contact with the reverse surface of the foil and transports the received liquid to a location exposed to microwave energy wherein the liquid is vaporized and recycled within the heating chamber 5. The method as disclosed is primarily for defrosting and heating frozen convenience food packaged on aluminum foil trays in paper containers.
Peter N. Stevenson (U.S. Pat. No. 3,615,713 issued on Oct. 26, 1971) disclosed a cooking utensil set for various foodstuffs that constitute a meal and are each contained in separate containers for the purpose of cooking the foodstuffs in a microwave oven. The patent discloses that individual containers are constructed so that different degrees of radiation occur to the foodstuffs contained therein, thereby allowing the cooking of a complete meal at one time. The cooking utensil set discloses utilizing suitable opaque materials such as copper, steel, or other metals for the individual containers to control the rate of cooking so that all the individual items are brought up to temperature simultaneously and illustrates the use of aluminum foil covered by a cardboard or plastic warpper as a suitable opaque material. The rate of cooking is disclosed as being controlled by having holes or openings 12 placed in them to allow selected amounts of radiation to penetrate the package and bring the material within up to the desired temperature, and that the number and size of holes is determined according to the normal serving temperature of the material within, the electrical characteristics of the material within, and the time the material is in the oven. Other disclosed embodiments for controlling the rate of cooking are disclosed as controlling the amount of reflective or opaque material per unit volume of solvent or suspension that is sprayed or deposited on the individual packages; fabricating the container of a reflective material that can be scored or etched to provide the desired irradiation; and controlling the thickness of the reflective or opaque material that is used to surround the package, very thin layers of essentially reflective material actually transmitting or allowing to penetrate small amounts of radiation, the amount of penetration being a function of the thickness of the material. This disclosure makes no mention of the benefits nor anticipates having an item such as popcorn cooked in a transparent medium and than have the popped corn transferred by means such as gravity to a microwave opaque container to prevent the popped corn from continued heating and eventual burning as the unpopped corn continues to pop. The disclosure also states that the enclosed items are continuously enclosed in the opaque materials from the time before they are placed in the microwave oven, during the microwave cooking process, and are only removed from the opaque material after the complete cooking process is over and after the cooking utensil set is removed from the microwave oven. The set as also disclosed is transient and disposable in nature.
Additional prior patents which may be of interest are listed below:
______________________________________ Patent No. Patentee(s) Issue Date ______________________________________ 3,716,606 Patrick S. Bazett February 13, 1973 4,183,435 Thompson et al. January 15, 1980 4,184,601 Stewart et al. January 22, 1980 4,205,114 Canterino et al. May 27, 1980 4,225,531 Harold A. Arbit March 10, 1981 4,256,944 Deryck Brandon March 17, 1981 4,281,083 Harold A. Arbit July 28, 1981 4,286,136 Stanley I. Mason, Jr. August 25, 1981 4,294,858 Rex E. Moule October 13, 1981 4,315,573 Bradley et al. February 16, 1982 4,327,136 Thompson et al. April 27, 1982 4,347,216 Kawasaki et al. August 31, 1982 4,348,572 Rex E. Moule September 7, 1982 4,353,890 George V. Scott October 12, 1982 4,387,012 Harold A. Arbit June 7, 1983 4,391,833 Self et al. July 5, 1983 4,404,241 Mueller et al. September 13, 1983 (PCT) WO White et al. December 24, 1980 80/02902 ______________________________________
3. General Discussion of the Invention
A popcorn popper for popping popcorn in a microwave oven comprising a popping section transparent to microwaves for popping the kernels of unpopped popcorn; and an essentially microwave opaque section or container located below the popping section and having at least one opening for receiving the popped corn. The essentially microwave opaque section receiving the kernels of popped corn as they fall through the opening(s), storing the popped corn and preventing the kernels of popped corn from burning as the kernels of unpopped corn continue to pop.
The popping section comprises a means for holding the kernels of unpopped corn until they are popped by the microwaves and includes a preferential clear containment means which surrounds the means for holding the kernels of unpopped corn. The preferential clear containment means permitting visual observance of the popping process while preventing the kernels of popped corn as they pop from leaving the containment of the popper and falling into the cavity of the microwave oven.
The essentially microwave opaque section need only be made from a material which only needs to reflect or absorb sufficient amounts of microwave radiation to prevent the burning of the popped corn received by the essentially microwave opaque section during the remainder of the popping process. The material can range from a material such as stainless steel which is very opaque to microwaves, to a combination of materials selected for their combination of reflection and absorption of microwaves.
The opening(s) into the essentially microwave opaque section preventing essentially the entrance of microwaves having a wavelength longer than the width or measurement of the opening. An exemplary width or measurement of 2 centimeters preventing the entrance of microwaves having a frequency equal to or less than 15 gigahertz.
The invention also includes an automatic buttering device which supplies melted butter to the kernels of popped corn and which is intended for use in a microwave oven or the like environment. The buttering device has a timing means for allowing the melted butter or margarine or the like to be automatically delivered at the end of a time delay period to the kernels of popped corn. The timing means includes a time delay means and preferably a manually adjusting means to allow the user to control and select the length of the time delay period before the melted butter is supplied to the popped kernels of corn. This allows the user to best control the supply of melted butter, allowing the melted butter to be delivered to a substantial amount of popped corn, and not prematurely to an empty container or a container containing only substantially small amounts of popped corn.
It is an object of the present invention to present a popcorn popper for use in a microwave oven or the like environment which has a popping section transparent to microwaves and an essentially microwave opaque section for receiving and storing the kernels of popped corn until at least the popping process is finished, the essentially microwave opaque section reflecting or absorbing enough microwave radiation to prevent the burning of the popped corn.
It is a further object of the present invention to present a popcorn popper for use in a microwave oven or the like environment which allows to the user at least three methods of timing the popping process: (1) the use of the built in microwave timer or other timing means; (2) audible by the lack of popping sound indicating the popping process is finished; and (3) visual by observing through the clear containment means that the popcorn has ceased to pop.
It is an even further object of the present invention to present an automatic buttering device for supplying melted butter to the kernels of popped corn which is intended for use in a microwave oven or the like environment, the buttering device having a timing means for allowing the supply of melted butter or margarine or the like to be automatically delivered at the end of a time delay period to the kernels of popped corn, allowing the user to best control the supply of melted butter and allow the melted butter to be delivered to a substantial amount of popped corn, and not prematurely to an empty container or a container containing only very small amounts of popped corn.